The Type 7s have never had LED signs. The LCD signs (which are the worst sign technology in the history of mankind) and automated announcements date to the early 2000s when they were being upgraded to trainline with the Type 8s.

EDIT: Oops, I was only thinking about the exterior signs. The interior LED displays date from the same period. That's what I get for posting before breakfast.

"The destination of this train is [BEEP BEEP]" -announcement on an Ashmont train.